An Empirical Evaluation of Touch and Tangible Interfaces for Tabletop Displays

paper

This paper compares several different methods for interacting on a table type display. They have implemented a touch based interface as well as a model-based interface on a single surface. They compared the touch and model based interaction for a variety of computing tasks and found that touch was better for some tasks and models were better for other tasks.

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I personally have never played around with any model based interfaces. I can see the usefulness of such an interface, though I am not sure that many small pieces would be such a good thing.